This invention relates in general to antifriction bearings and more particularly to a bearing having sensors which monitor conditions under which the bearing operates.
Antifriction bearings have rolling elements which roll along raceways on races to significantly reduce friction between a shaft and a housing or between similar components, one of which rotates relative to the other. The rolling elements and raceways require lubrication which often takes the form of grease, and of course, they should be isolated from contaminants such as dirt and water. Seals fitted to the ends of the bearings serve this purpose. Thus, the critical surfaces of antifriction bearings are not exposed and cannot be inspected without removing the bearing from its installation and disassembling it. Indeed, some bearings, such as those used for journals on railcars and those used on mill rolls, are disassembled at periodic intervals for inspection, cleaning and relubrication.
To be sure, devices exist which are designed to monitor operating conditions of bearings. Most sense temperature. For example, railroads use track-side infrared sensors to detect overheated journal bearings in passing trains. Some bearings even come equipped with temperature sensors. In this regard, the absence of adequate lubrication will cause the temperature of a bearing to rise. Also, where a bearing race slips within a housing or on a shaft, the temperature in the bearing will rise owing to the high friction where the slippage occurs. Seizure, as when a rolling element becomes wedged between races, produces an extreme form of slippage. While heat may signal or mark a bearing failure, its presence often does not provide adequate time to avoid a failure.
Apart from the problems identified with detecting bearing failure, bearing races tend to rotate or creep in the structures in which they are mounted, particularly when subjected to shocks. Typical are the outer races of railcar journal bearings which tend to creep in the adaptors for the truck side frames in which they are located. But sometimes creep should be avoided. For example, a refurbished bearing may have a slightly fatigued area in its stationary race and that area should be kept out of the load zone. Also, a bearing equipped with a wired sensor cannot tolerate creep in the race that actually carries the sensor, since creep will eventually sever the electrical leads that connect the sensor with a device for processing the signal generated by the sensor.
The present invention resides in a bearing having a sensor module containing multiple sensors which produce signals that reflect various operating conditions of the bearing, such as angular velocity, temperature and acceleration. The sensor module fits into or adjacent to one of the races. In addition. the invention resides in a bearing having a round outer race equipped with blocks that prevent it from rotating in a housing .